Find fuzzy matches using Levenshtein distance (requires fuzzystrmatch extension)
AI agents call fuzzy_match to retrieve information from Postgres Mcp Legacy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a read-only string similarity search using Levenshtein distance algorithm. It retrieves or identifies matches from existing data without creating, modifying, deleting, or executing arbitrary code. This is a passive data retrieval operation with no side effects, placing it squarely in the Read category.
From the tool's definition Tool name 'fuzzy_match' and description 'Find fuzzy matches using Levenshtein distance' indicates a search/query operation that retrieves matching data without modification or deletion.
Documented attack patterns abuse exactly the kind of access fuzzy_match gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres Mcp Legacy, and nothing reaches the server without passing your rules. This is the rule we recommend for fuzzy_match:
{
"version": "1",
"default": "deny",
"tools": {
"fuzzy_match": {}
}
}fuzzy_match is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Find fuzzy matches using Levenshtein distance (requires fuzzystrmatch extension). It is categorised as a Read tool in the Postgres Mcp Legacy MCP Server, which means it retrieves data without modifying state.
Register the Postgres Mcp Legacy MCP server in PolicyLayer and add a rule for fuzzy_match: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Postgres Mcp Legacy. Nothing to install.
fuzzy_match is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the fuzzy_match rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for fuzzy_match. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
fuzzy_match is provided by the Postgres Mcp Legacy MCP server (neverinfamous/postgres-mcp-legacy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Postgres Mcp Legacy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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60 Postgres Mcp Legacy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.